The Earthquake and Eruption Prediction Research and Observation Center of Tohoku University and the Earthquake Research Institute of the University of Tokyo detect P and S waves caused by the bomb low pressure generated in the Atlantic Ocean and clarify the mechanism of their generation by quantifying the epicenter information. It was announced that it was published in the US scientific journal "Science".
The "structural exploration method" using seismic waves plays a large role in understanding the internal structure of the earth, but its resolution has been constrained by the bias of the seismic distribution.In order to solve this problem, a method to extract the structure between observation points using the pulsation excited by ocean waves was developed so that the crustal structure and upper mantle structure are actually determined in many areas. became.However, even with this method, the estimation of the structure is still constrained by the distribution of observation points.
Since "body waves" such as P waves and S waves travel deep in the earth, they are important for estimating the internal structure of the earth, but there are many unsolved problems and the existence of S waves is expected. However, it has not been actually observed.
In December 2014, an explosive cyclogenesis occurred in the Atlantic Ocean, causing damage to Britain and Ireland.At that time, the P wave generated by the ocean wave travels deep in the earth and reaches Japan.Therefore, the research team analyzed the seismic waves recorded at this time using the data of the seismograph observation network "Hi-net" and investigated how the sea waves caused the seismic waves.As a result, it was possible to detect two S waves, SH wave and SV wave, for the first time at the same time as detecting P wave with a period of 12-5 seconds.
Next, when the epicenter was investigated, it was found that the position was linked to the movement of the cyclone and moved along the contour line.Furthermore, as a result of comparing with the theoretically predicted value of P wave using the ocean wave model for more quantitative verification, it is clear that both the epicenter position and intensity are consistent with the theoretical value and the value estimated from the observation. became.However, it is still difficult to make a quantitative comparison of S waves, and it will be necessary to improve the theory in the future.
In this study, it was shown that the body wave caused by the storm can be represented by a point source.In the future, we will collect and catalog examples of strong meteorological phenomena that will occur in various parts of the world, aiming to estimate the internal structure of the earth, especially in the southern hemisphere where there are no earthquakes and no seismographs.
